StoneFly DR365V vs Datto SIRIS: MSP Backup Appliance Compared (2026)

Two camps have emerged. In one camp, appliances built around a named backup stack (usually Veeam) sitting on hardened, air-gapped storage. In the other, appliances built as part of a full PSA/RMM/backup bundle where the backup is one piece of a broader service delivery suite.

StoneFly DR365V is the first pattern. Datto SIRIS is the second. Both will back up your customer's servers and restore them when a ransomware event hits. The real question is whether the bundle around the appliance serves your business model or constrains it.

We distribute DR365V because the air-gapped vault and Veeam ecosystem give MSPs an independent posture, the appliance doesn't care which PSA, which cloud, or which hypervisor you run. Datto SIRIS makes sense for practices that have standardised on Kaseya end to end. Both are credible, but they answer different questions.

Datto SIRIS is designed as a closed loop. The agent format is proprietary, the off-site replication target is Datto Cloud, and the verification + recovery tooling is all Datto software. This gives Datto control over the full chain, which is why screenshot verification has been so polished for so long. But it also means your data, your catalogue, and your recovery points all live inside one vendor's ecosystem. If you ever want to move off Datto, you're rebuilding from agents up.

The DR365V is the opposite shape. Veeam Backup & Replication runs the jobs, a hardened Linux repo on StoneFly storage is the local immutable target, and off-site replication can go to any S3-compatible endpoint. Your backup catalogue is portable Veeam metadata. You can replace the appliance without touching the software, replace the software without touching the appliance, or switch cloud targets without re-architecting the off-site tier.

For MSPs building a long-term service practice, vendor optionality matters more than any single feature. That's the DR365V pitch in one sentence.

Both products can survive a ransomware event if configured correctly. The details are different.

DR365V runs immutability at the storage layer. Backups land on a hardened Linux repo where the filesystem attributes prevent modification or deletion for a configurable retention window. The appliance also operates an air-gapped vault on a second tier that comes online only during scheduled backup windows, then disconnects. Ransomware traversing the backup network never touches the vault copy. Veeam's own immutability logic layers on top.

Datto SIRIS relies primarily on cloud-side protection. Local appliance backups are not immutable by default, the protection model assumes that even if the on-premises appliance is compromised, the Datto Cloud replica survives. This works in practice but it means your recovery path depends on cloud bandwidth and Datto's recovery tooling, not a local vault you can spin up on your own network.

For organisations with tight RTOs (under 4 hours for mission-critical systems), the local air-gapped vault on DR365V is the more defensible architecture. For smaller sites where cloud recovery is acceptable, the Datto model is simpler to operate.

Exact numbers vary by capacity, but the pricing shapes are different enough that the five-year picture diverges materially.

Datto SIRIS is priced per protected agent plus Datto Cloud storage, invoiced monthly. There is no capex on the appliance itself; it's included in the subscription. Attractive on the surface, but the per-agent recurring fee compounds as your customer base grows, and Datto Cloud storage is priced at a significant premium to generic S3.

DR365V is a one-off capex for the appliance plus annual Veeam licensing plus your chosen cloud target. You buy the discs, you own the discs, and you scale capacity by adding drives rather than paying a per-TB monthly fee forever. Cloud replication to Wasabi Sydney or StoneFly Cloud Vault typically sits at a third of Datto Cloud pricing.

The crossover point depends on scale. Below ~30 protected servers, SIRIS is often cheaper in year one. Between 30 and 100 servers, DR365V becomes cheaper by year two. Above 100 servers, DR365V is materially cheaper on a five-year view. CRS will run the specific numbers against your customer list if you ask.

Choose Datto SIRIS when:

• You run Autotask PSA, Datto RMM, and IT Glue as your core service-delivery stack.
• Screenshot verification and instant virtualisation in Datto Cloud are selling features to your customer base.
• Your typical site is small (under 30 servers) and short-term subscription economics matter more than long-term TCO.
• You want a single vendor bill for PSA, RMM, and backup.

Choose StoneFly DR365V when:

• Air-gapped local immutability is a hard requirement (Essential Eight maturity, APRA CPS 234, ISO 27001).
• You already run Veeam and want the Veeam catalogue as your portable backup metadata.
• You need Proxmox VE backup support natively (Datto is behind here).
• You're scaling past 30 servers and the five-year TCO matters more than the first-year price.
• You want optionality on your cloud replication target.

Cloud Ready Solutions is the ANZ and Pacific distributor for StoneFly. DR365V ships to partners across Australia, New Zealand, Fiji, and PNG with AUD invoicing and local support. Partners who onboard with us get:

• Sizing consultation: capacity modelling against your protected workload inventory, disc tier selection, retention policy design.
• Veeam licensing: bundled VBR licences invoiced alongside the appliance.
• Cloud replication target options: StoneFly Cloud Vault (Wasabi-backed, immutable, Sydney), Wasabi direct, or your own S3 destination.
• Deployment runbook: the CRS Veeam-on-DR365V deployment checklist used by partners on dozens of production rollouts.
• Escalation: direct line into StoneFly engineering for issues that need upstream attention.

See also: StoneFly DR365V product page, Keepit vs Datto for the SaaS-backup equivalent comparison.